Explore topic-wise MCQs in Electrical Engineering Questions.

This section includes 131 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

51.

Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
A. Series motor
B. Shunt motor
C. Cumulatively compounded motor
D. Differentially compounded motor
Answer» D. Differentially compounded motor
Discussion
52.

Which of the following motor is preferred for operation in highly explosive atmosphere ?
A. Series motor
B. Shunt motor
C. Air motor
D. Battery operated motor
Answer» D. Battery operated motor
Discussion
53.

If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens__________?
A. nothing will happen to the motor
B. this will make armature to take heavy current, possibly burning it
C. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
D. motor will run at very slow speed
Answer» D. motor will run at very slow speed
Discussion
54.

D.C. series motors are used______________?
A. where load is constant
B. where load changes frequently
C. where constant operating speed is needed
D. in none of the above situations
Answer» E.
Discussion
55.

Sparking at the commutator of a D.C. motor may result in____________?
A. damage to commutator segments
B. damage to commutator insulation
C. increased power consumption
D. all of the above
Answer» E.
Discussion
56.

If the supply voltage for a D.C. motor is increased, which of the following will decrease ?
A. Starting torque
B. Operating speed
C. Full-load current
D. All of the above
Answer» D. All of the above
Discussion
57.

Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?
A. Providing laminations in armature core
B. Providing laminations in stator
C. Using non-magnetic material for frame
D. Using material of low hysteresis co-efficient for armature core material
Answer» E.
Discussion
58.

D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the________________?
A. series motor
B. shunt motor
C. compound motor
D. any of the above
Answer» B. shunt motor
Discussion
59.

Which of the following loss in a D.C. generator varies significantly with the load current ?
A. Field copper loss
B. Windage loss
C. Armature copper loss
D. None of the above
Answer» D. None of the above
Discussion
60.

Which of the following motors is most suitable for signalling devices and many kinds of timers ?
A. D.C. shunt motor
B. D.C. series motor
C. Induction motor
D. Reluctance motor
Answer» E.
Discussion
61.

In a D.C. generator all of the following could be the effects of iron losses except___________?
A. Loss of efficiency
B. Excessive heating of core
C. Increase in terminal voltage
D. Rise in temperature of ventilating air
Answer» D. Rise in temperature of ventilating air
Discussion
62.

The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ?
A. hysteresis loss
B. field copper loss
C. armature copper loss
D. eddy current loss
Answer» D. eddy current loss
Discussion
63.

Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of_____________?
A. D.C. series motor
B. D.C. shunt motor
C. induction motor
D. all of above motors
Answer» B. D.C. shunt motor
Discussion
64.

Which of the following motors is usually used in house-hold refrigerators ?
A. D.C. shunt motor
B. D.C. series motor
C. Single phase induction motor (split phase start or induction run motor)
D. Reluctance motor
E. Synchronous motor
Answer» D. Reluctance motor
Discussion
65.

Why are the D.C. motors preferred for traction applications ?
A. Torque and speed are inversely proportional to armature current
B. Torque is proportional to armature current
C. Torque is proportional to square root of armature current
D. The speed is inversely proportional to the torque and the torque is proportional to square of armature current
Answer» E.
Discussion
66.

Which motor should not be started on no-load ?
A. Series motor
B. Shunt motor
C. Cumulatively compounded motor
D. Differentially compounded motor
Answer» B. Shunt motor
Discussion
67.

The speed of a D.C. shunt motor can be increased by_______________?
A. increasing the resistance in armature circuit
B. increasing the resistance in field circuit
C. reducing the resistance in the field circuit
D. reducing the resistance in the armature circuit
Answer» C. reducing the resistance in the field circuit
Discussion
68.

For constant torque drive which speed control method is preferred ?
A. Field control
B. Armature voltage control
C. Shunt armature control
D. Mechanical loading system
Answer» C. Shunt armature control
Discussion
69.

Ward-Leonard control is basically a____________?
A. voltage control method
B. field divertor method
C. field control method
D. armature resistance control method
Answer» B. field divertor method
Discussion
70.

If I2 be the armature current, then speed of a D.C. shunt motor is_______________?
A. independent of Ia
B. proportional to la
C. varies as (Ia)
D. varies as la
Answer» B. proportional to la
Discussion
71.

Which motor has the poorest speed control?
A. Differentially compounded motor
B. Cumulatively compounded motor
C. Shunt motor
D. Series motor
Answer» E.
Discussion
72.

For a D.C. shunt motor if the excitation is changed_______________?
A. torque will remain constant
B. torque will change but power will remain constant
C. torque and power both will change
D. torque, power and speed, all will change
Answer» C. torque and power both will change
Discussion
73.

In a differentially compounded D.C. motor, if shunt field suddenly opens____________?
A. the motor will first stop and then run in opposite direction as series motor
B. the motor will work as series motor and run at slow speed in the same direction
C. the motor will work as series motor and run at high speed in the same direction
D. the motor will not work and come to stop
Answer» B. the motor will work as series motor and run at slow speed in the same direction
Discussion
74.

The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is______________?
A. 4.0
B. 2.0
C. 1.0
D. 0.5
Answer» E.
Discussion
75.

Three point starter can be used for______________?
A. series motor only
B. shunt motor only
C. compound motor only
D. both shunt and compound motor
Answer» E.
Discussion
76.

The condition for maximum power in case of D.C. motor is______________?
A. back e.m.f. = 2 x supply voltage
B. back e.m.f. = | x supply voltage
C. supply voltage = | x back e.m.f
D. supply voltage = back e.m.f
Answer» C. supply voltage = | x back e.m.f
Discussion
77.

Which of the following motor has the poorest speed regulation ?
A. Shunt motor
B. Series motor
C. Differential compound motor
D. Cumulative compound motor
Answer» C. Differential compound motor
Discussion
78.

The armature torque of the D.C. shunt motor is proportional to____________?
A. field flux only
B. armature current only
C. both A. and B.
D. none of the above
Answer» C. both A. and B.
Discussion
79.

As -the load is increased the speed of D.C. shunt motor will____________?
A. reduce slightly
B. increase slightly
C. increase proportionately
D. remains unchanged
Answer» B. increase slightly
Discussion
80.

In D.C. machines the residual magnetism is of the order of_________________?
A. 2 to 3 per cent
B. 10 to 15 per cent
C. 20 to 25 per cent
D. 50 to 75 per cent
Answer» B. 10 to 15 per cent
Discussion
81.

For which of the following applications a D.C. motor is preferred over an A.C. motor ?
A. Low speed operation
B. High speed operation
C. Variable speed operation
D. Fixed speed operation
Answer» D. Fixed speed operation
Discussion
82.

Following motor is used where high starting torque and wide speed range control is required?
A. Single phase capacitor start
B. Induction motor
C. Synchronous motor
D. D.C. motor
E. None of the above
Answer» E. None of the above
Discussion
83.

Which D.C. motor is generally preferred for cranes and hoists ?
A. Series motor
B. Shunt motor
C. Cumulatively compounded motor
D. Differentially compounded motor
Answer» B. Shunt motor
Discussion
84.

Sparking, is discouraged in a D.C. motor because_____________?
A. it increases the input power con-sumption
B. commutator gets damaged
C. both A. and B.
D. none of the above
Answer» C. both A. and B.
Discussion
85.

Speed control by Ward Leonard method gives uniform speed variation_____________?
A. in one direction
B. in both directions
C. below normal speed only
D. above normal speed only
Answer» C. below normal speed only
Discussion
86.

Which of the following method of speed control of D.C. machine will offer minimum efficiency ?
A. Voltage control method
B. Field control method
C. Armature control method
D. All above methods
Answer» D. All above methods
Discussion
87.

Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be_____________?
A. level compounded
B. under compounded
C. cumulatively compounded
D. differentially compounded
Answer» D. differentially compounded
Discussion
88.

The plugging gives the____________?
A. zero torque braking
B. smallest torque braking
C. highest torque braking
D. none of the above
Answer» D. none of the above
Discussion
89.

The armature voltage control of D.C. motor provides____________?
A. constant torque drive
B. constant voltage drive
C. constant current drive
D. none of the above
Answer» B. constant voltage drive
Discussion
90.

Usually wide and sensitive speed control is desired in case of____________?
A. centrifugal pumps
B. elevators
C. steel rolling mills
D. colliery winders
Answer» E.
Discussion
91.

The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is______________?
A. 2.36%
B. 4.76%
C. 6.77%
D. 8.84%
Answer» C. 6.77%
Discussion
92.

Which of the following motors one will choose to drive the rotary compressor ?
A. D.C. shunt motor
B. D.C. series motor
C. Universal motor
D. Synchronous motor
Answer» E.
Discussion
93.

If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor_____________?
A. of lower H.P. should be selected
B. of higher H.P. should be selected
C. can be used for 50°C ambient temperature also
D. is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor
Answer» E.
Discussion
94.

If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking?
A. regenerative
B. plugging
C. dynamic braking
D. none of the above
E. any of the above
Answer» C. dynamic braking
Discussion
95.

The armature voltage control of D.C. motor provides_____________?
A. constant voltage drive
B. constant current drive
C. constant torque drive
D. none of the above
Answer» D. none of the above
Discussion
96.

If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will_________?
A. increase
B. decrease
C. remain same
D. become zero
Answer» B. decrease
Discussion
97.

Regenerative method of braking is based on that___________?
A. back e.m.f. is less than the applied voltage
B. back e.m.f. is equal to the applied voltage
C. back e.m.f. of rotor is more than the applied voltage
D. none of the above
Answer» C. back e.m.f. of rotor is more than the applied voltage
Discussion
98.

In Ward-Leonard control the lower limit of speed is imposed by________?
A. residual magnetism of the generator
B. core losses of motor
C. mechanical losses of motor and generator together
D. all of the above
Answer» B. core losses of motor
Discussion
99.

The hysteresis loss in a D.C. machine least depends on____________?
A. Frequency of magnetic reversals
B. Maximum value of flux density
C. Volume and grade of iron
D. Rate of flow of ventilating air
Answer» E.
Discussion
100.

The main disadvantage of the Ward-Leonard control method is______________?
A. high initial cost
B. high maintenance cost
C. low efficiency at Hght loads
D. all of the above
Answer» E.
Discussion